[cfe-dev] Cquery vs Clangd

[Manuel Klimek via cfe-dev]

On Thu, Mar 1, 2018 at 7:50 PM Marc-André Laperle <
marc-andre.laperle at ericsson.com> wrote:

> Hi Manuel,
>
> A few relies below.
>
> On Thu, 2018-03-01 at 13:24 +0000, Manuel Klimek wrote:
>
> - cquery is based on libclang, while clangd directly works with the AST
> and provides a non-LSP C++ interface to be integrated as service in larger
> environments - this lets clagnd work in places where libclang is hard to
> integrate
>
>
> Would that C++ interface be usable for out-of-tree projects? I guess one
> would simply link to libclangDaemon?
>

Correct.


> - clangd wants to integrate with other folks in the community on indexing
> interfaces and mechanisms that provide a platform for tools to work on;
> while there is also some prototyping, a lot of work goes into designing the
> right system
> - clangd puts scale and performance first; for very very large code bases
> (significantly larger than chromium), this is a precondition, and (together
> with the previous item) why we don't have a global index yet
>
>
> I think cquery puts those two first but it sounds like you have even more
> agressive requirements.
>

Unfortunately, yep :)


> - clangd work currently focuses on making code completion really good, so
> quite a bit of work has gone into how to split the preamble and making
> completion results better (which also benefits cquery \o/)
>
> The hope is that clangd at some point will catch up with cquery, but as
> those things go, in the end they will probably have slightly different
> trade-offs, so some folks will use one while others use the other. In
> principle that's the nice thing about the LSP; competition is now possible
> :)
>
>
> Yeah, clients can adopt one of the other pretty easily (well maybe without
> extension support). I think it's good to understand the different
> trade-offs and compare the different goals so that potential contributors
> can decide where to focus their work.
>

Yep. I'd say if one wants to contribute to continuing to build up a
platform for C++ tooling based on clang, get involved in clangd (I believe
this is specifically a non-goal for cquery); if one wants to get new useful
features as fast as possible, cquery is a better place, and the clangd code
reviews will likely turn out to be a source of frustration, as it often
involves getting consensus across a range of people from different
companies :)

For everyone interested, come join the talk on clangd at the Euro LLVM in
> Bristol; that talk will include a more detailed comparison between the two
> approaches.
>
>
> That sounds very good. I'll be there!
>
> Thank you for your time,
> Marc-André
>
>
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